A time-of-flight camera (ToF camera) is a range imaging camera system that resolves distance based on the known speed of light, measuring the time-of-flight of a light signal between the camera and the subject for each point of the image. A time-of-flight camera generally includes an illumination unit that illuminates the subject with light modulated with frequencies up to 100 MHz. The illumination unit normally uses infrared light to make the illumination unobtrusive. A lens can be used to gather the reflected light and images the environment onto an image sensor, with an optical band-pass filter passing only the light with the same wavelength as the illumination unit. This helps suppress non-pertinent light and reduce noise. At the image sensor, each pixel measures the time the light has taken to travel from the illumination unit to the object and back to the sensor. From this time, a distance to the subject at that point can be determined.